21609728784031 has 2 divisors, whose sum is σ = 21609728784032. Its totient is φ = 21609728784030.

The previous prime is 21609728783971. The next prime is 21609728784079. The reversal of 21609728784031 is 13048782790612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21609728784031 - 2⁴¹ = 19410705528479 is a prime.

It is a super-2 number, since 2×21609728784031² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21609728785031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10804864392015 + 10804864392016.

It is an arithmetic number, because the mean of its divisors is an integer number (10804864392016).

Almost surely, 2^{21609728784031} is an apocalyptic number.

21609728784031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21609728784031 is an equidigital number, since it uses as much as digits as its factorization.

21609728784031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8128512, while the sum is 58.

The spelling of 21609728784031 in words is "twenty-one trillion, six hundred nine billion, seven hundred twenty-eight million, seven hundred eighty-four thousand, thirty-one".